Database Research Summaries2018 Fungicide Resistance in Rhizoctonia solani and Implications for Soybean Fields in Nebraska
The focus of this project is to determine the sensitivity of isolates to commercial fungicides with different modes of action and to characterize the structure of pathogen populations within and between fields.
- Perform a comprehensive survey of soybean fields for R. solani.
- Determine fungicide sensitivity of each isolate to selected commercial fungicides.
- Identify the most prevalent anastomosis groups (within-species subgroups).
- Develop and apply genetic markers to characterize the structure of populations within the two most prevalent R. solani subgroups.
- This survey has provided novel information, which shows that Rhizoctonia zeae (Waitea circinata var. zeae) is an important pathogen of soybean, which has not been well studied.
- We have identified Rhizoctonia zeae and Rhizoctonia solani AG-4 as the two most prevalent groups in Nebraska, among a total of more than 100 Rhizoctonia isolated. Our work is further characterizing the level of pathogenicity of these isolates and has identified a surprising number of Rhizoctonia zeaethat are pathogenic to soybean.
- Current results show that Rhizoctonia zeae has a broad range of fungicide sensitivity to prothioconazole, sedaxane, and fludioxonil. However, results of our research to date suggest that Rhizoctonia zeae is completely insensitive to azoxystrobin fungicide, which is currently one of most common fungicides used due to the expected high specificity of action.
- This is the first research to conduct a detailed investigation into seedling diseases caused by Rhizoctonia on soybean in Nebraska. The findings during this study shows that Rhizoctonia zeae and Rhizoctonia solani AG-4 are the two groups among Rhizoctonia that pose the highest risk to soybean production.
- This work also shows that there is variability in fungicide sensitivity of Rhizoctonia zeae and our current results suggest it is insensitive to azoxystrobin (QoI fungicides).
- Development of molecular markers that is currently underway will provide deeper insight into the biology of this pathogen and how it may be spread, which are important for creating robust management recommendations.
For more information about this research project, please visit the National Soybean Checkoff Research Database.
Funded in part by the soybean checkoff.